Many devices or objects of daily life are operated today by input apparatus such as for example electric switches, control levers, touchscreens, slide controls, keyboards and the like where feedback occurs via other sensory organs than the input. If, for example, a cursor on a monitor shall be controlled by a so-called mouse, input occurs by manual movement of the mouse whereas feedback occurs visually by viewing the monitor. If the volume of a radio shall be modified, today in many units a key is only held down, with the duration of pressing determining the degree of volume change. Here, the feedback occurs acoustically.
It is desirable to receive a direct haptic feedback on tactile entry, with tactile entry (force, displacement, direction) being available for haptic experience directly and not occurring only by a possibly time-delayed system, such as for example via a signal not directly associated with the entry.
Magnetically positioned input devices are suitable for this.
EP 1 223 541 B1 describes an input apparatus in the form of a remote control, in which for control of a cursor on a display screen a movable, adjustable portion with a first magnet mounted on it is displaced relative to a second stationary magnet and the resulting magnet field is measured by means of Hall sensors from which the position of the movable, adjustable portion can be determined. Due to the interaction of the two magnets, the adjustable portion in the absence of external forces is put into a predetermined position. Only by external force, for example by a finger of an operator, the adjustable portion can be displaced out of this rest position, with the force required for displacement being dependent on the position of the magnets to each other, so that the user receives a tactile or haptic feedback.
A third stationary magnet may also be provided so that the adjustable portion can be displaced between two rest positions, with displacement out of both rest positions each requiring an external force.
Further examples of input apparatus with magnets are known from the following documents:
DE 10117956 B4, DE 102005018275 A1,
DE 102007002189 A1, DE 202005019271 U1,
EP 0810544 A2, EP 1901005 A2,
JP 06318134 A, JP 2005004365 A,
U.S. Pat. No. 5,504,502 A, U.S. Pat. No. 7,187,360 B2,
U.S. Pat. No. 7,489,296 B2, U.S. 2002/0054012 A1,
U.S. 2002/0125977 A1, U.S. 2004/0252104 A1,
U.S. 2005/0068134 A1, U.S. 2006/0209019 A1,
WO 03/054782 A1, WO 2006/130723 A2,
WO 2006/131520 A1 and WO 2008/016386 A2.
Most of the above mentioned documents use Hall sensors, which measure magnetic flux density, from which a signal for the position of the movable magnet can be derived.
WO 00/70438 points out that the Hall sensors are quite expensive and can only measure magnetic flux density so that for detecting a direction of displacement of a magnet at least two Hall sensors are required. This document therefore suggests to use coils as sensors. If a magnet is displaced relative to the coil, voltage is induced in the coil, with a voltage impulse also permitting detection of the direction of motion since the voltage impulse depending on the direction of motion starts with a rising or falling edge.
Disadvantageous in this apparatus, however, is that only a displacement can be detected and no static condition.
U.S. Pat. No. 5,698,976 A describes an input device with a board out of magnetic material the surface of which in X and Y direction has a regular but different geometrical configuration in the form of elevations and recesses. A magnet can be displaced relative to said board and a sensor in the form of a coil is displaced together with the magnet. Due to the varying geometry on the board surface, the magnetic flux varies which is detected by the coil.